Left bundle area pacing in hypertrophied hearts: An ex vivo ovine model to study deployment of pacing leads in thick septum.

BACKGROUND

Knowledge of lead biomechanics in a hypertrophied interventricular septum (IVS) may improve the success rate of left bundle branch area pacing (LBBAP) in these patients.

OBJECTIVES

We sought to investigate the biomechanics of lead penetration in an ex vivo ovine model of a hypertrophied IVS and compare the behavior of lumenless leads (LLL) vs stylet-driven leads (SDL) in terms of torque transfer and penetrating capacity.

METHODS

Twenty fresh ex vivo ovine interventricular septae were excised to create a virtual hypertrophied IVS model by having 2 septae sandwiched together and placed in a custom-made clamp. Five different leads were driven into the hypertrophied IVS model with sheath support via a custom-engineered tool which allowed control of input rotation, forward movement, and measurement of torque transfer curves.

RESULTS

A total of 100 lead runs were completed which revealed the following 5 distinct patterns of lead behavior: (1) endocardial entanglement, (2) endocardial barrier, (3) drill, (4) myocardial barrier (only observed using LLL, P<.001), and (5) screwdriver (only observed using SDL, P<.001). The maximum torque during successful and deep penetration trended lower compared with when the lead failed to penetrate 2.78 ± 1.21 mN vs 3.6 mN ± 1.62 mN (P = .085). SDL was able to achieve a greater depth of penetration compared with the LLL (20.89 ± 6.46 mm vs 14.8 ± 2.39 mm; P<.001).

CONCLUSION

Lead deployment patterns in hypertrophied septae vary between leads. SDL achieves deeper septal penetration at lower torque and faster forward motion than LLL.